No abstract

The current work was designed to assess the effect of modification of model digester on the kinetics that affects efficiency in biogas generation using bovine rumen content as the feedstock. A biogas plant consisting of conventional and modified fixed-dome digesters (each with 2 m 3 capacity) was established; and bovine rumen content was used as feedstock. Standard methods were used to determine the kinetic (physicochemical and microbiological) parameters. Identification of fungal and bacterial species involved in the process was carried out by genomic study of the 18S rRNA and 16S rRNA regions, respectively; amplified using universal forward and backward primers for fungi (NS1/NS4), bacteria ((515F/926R) and archaea (Met86F/Met140R); submitted to GenBank and analysed using Blast Programme at National Centre for Biotechnology Information website. A mass balance approach was used to estimate the theoretical gas yield from the total solid/volatile sold lost. It was found that the temperature in both modified and conventional digesters was uniform throughout the hydraulic retention time, between 32 to 34.5C, indicating a mesophilic range. The pH level was found to be lower in the modified digester compared to the conventional digester, indicating higher accumulation of organic acids. The mean total solid was found to drop from 12.49±0.53 to 3.82±0.21 in the modified digester after digestion, while this was from 13.30±0.4 to 6.69±0.16 in the conventional digester. The mean volatile solid drops from 66.67±1.62 to 36.13±0.27 in the modified digester after digestion, while it was from 69.94±1.54 to 54.23±1.33 in the conventional digester. The theoretical biogas yield was higher in the modified digester (87 mg/l) compared to the conventional one (65 mg/l). The microbial counts were observed to be affected by the kinetic parameters in both the digesters. The organisms identified were: Lactobacillus acidophilus, Bacteroides nordii, Clostridium perfringens, Clostridium acetobutylicum, Proteus vulgaris, Methanosarcina sicilia, Methanosarcina mazei, Methanobrevibacter ruminantium, Fusarium solani, Fusarium graminearum, Aspergillus niger and Penicillium specie. Conclusively, the modified digester, under a manual stirring at 10 round/min, 3 times a day at an interval of six hours, has appreciably generated higher theoretical biogas yield after 8 weeks hydraulic retention time. The agitation of the slurry using the improvised stirrer in the modified digester has significantly facilitated the utilization of the bovine rumen content by the indigenous microorganisms. Modification of digester to enhance mixing of the feedstock should therefore be encouraged in household anaerobic digesters.

A water-soluble Atom transfer radical polymerisation (ATRP) initiator (1,2-dihydroxypropane-3oxy-2-bromo-2-methyl propionyl) has been synthesised by a two step reaction which involved esterification of the starting material and hydrolysis of the intermediate product. 1 H NMR of both the intermediate and final products has confirmed the structure of the targeted products and also the reactions produce high yield and sufficient purity. This initiator will be very useful in the polymerisation of water-soluble monomers in order to produce polymers with controlled molecular weight and narrow polydispersity.

In this study, a mathematical model for the trans-esterification reaction of Jatropha curcas seed Oil (JCO) was developed using Response Surface Methodology (RSM) in terms of some operational variables, namely: temperature (50 to 80°C), catalyst concentration (0.7 to 1% in relation to oil mass) and methanol/oil ratio (3:1-9:1), at fixed reaction time (90 min) and mixing intensity. Biodiesel was produced by trans-esterification of J. curcas seed oil with methanol using NaOH as catalyst. Optimum biodiesel yield of 88.64% was obtained at 7:1 molar ratio of methanol/oil, reaction temperature of 80°C and 0.8% catalyst loading. The biodiesel produced at 80°C, 7:1 methanol/oil ratio and 0.9% catalyst loading when blended with petro-diesel (B20) gave the highest Cetane number of 81.83. The results obtained indicated that the reaction temperature, methanol/oil ratio and catalyst concentration have significant effects on both the Cetane number and yield of biodiesel. Thus, the mathematical model developed can be used in the optimization and simulation of biodiesel yield during trans-esterification of vegetable oil within the range of the parameters studied.

The study's objective was to characterize the soils and carry out suitability evaluation of floodplain soils in Ardo-Kola, Taraba State. Six (6) profile pits were dug from two physiographic units and the most predominant land use (woodland area and arable land area). Three (3) profile pits were dug on each of the identified units using standard dimension. Soil morphological results indicated that the soils were sub-angular blocky, strong to fine structure, very sticky, hard when dry and firm when moist in the woodland area. Colour ranged from pale brown 10YR (6/3) to dark greyish brown 10YR (4/2). Soils in the arable land area were mostly very sticky, firm when moist and hard when dried. The colour ranged from light yellowish-brown 10YR (6/4) to dark grey 10YR (4/1). Results of particle size distribution were sandy loamy and loamy sand across the pedons. Bulk density values ranged from 1.50 to 1.67gm/cm3, and total porosity ranged from 37 to 43% respectively. The soils were generally moderately acidic to slightly acidic, organic carbon and total nitrogen was low (<2% and <0.15%), calcium and magnesium were rated medium (2-5cmol/kg and 0.3-1.0cmol/kg) respectively. Base saturation values were rated medium (50-80%) to high (>80%) across the pedons. Soil suitability result for the woodland area showed overall suitability for maize in pedon BYF1 was S3w (marginally suitable) with limitation in nutrient availability and suitable (S1) in pedon BYF5. Arable land area was also marginally suitable (S3) with limitation in oxygen availability except for pedon BYF4, which was not suitable (N) for maize cultivation. Woodland area was moderately suitable (S2) and suitable (S1) for the arable land area with limitation in texture except for pedon BYF 3 with limitation in oxygen availability. Rice production is encouraged in the arable land area while maize in the woodland area using fertilizers and organic materials to ameliorate low fertility limitations observed in the study area.